Circuit breaker for high power, high voltage networks



1967 ROXBURGH ETAL 3,3 5,

CIRCUIT BREAKER FOR HIGH POWER, HIGH VOLTAGE NETWORKS Filed March 27, 1964 2 Sheets-Sheet 1 ''E Fig. 1. v1

W. RP 91g -1P v 1967 A. ROXBURGH ETAL 3,30 57 CIRCUIT BREAKER FOR HIGH POWER, HIGH VOLTAGE NETWORKS 2 Sheetsl-Sheet 2 Filed March 27, 1964 Y isolator contact.

United States Patent 3,305,657 CIRCUIT BREAKER FOR HIGH POWER, HIGH VOLTAGE NETWORKS Albert Roxburgh, Stanmore, Middlesex, and Arthur Charles Gibson, London, England, assignors to Associated Electrical Industries Limited, London, England, a British company Filed Mar. 27, 1964, Ser. No. 355,331 Claims priority, application Great Britain, Apr. 1, 1963, 12,834/ 63 1 Claim. (Cl. 200-144) This invention relates to power switchgear and aims at providing an arrangement which is safe, reliable and compact, also requires less maintenance than conventional switchgear for similar duty.

Accordingly this invention resides in an electric power switchgear comprising a traversible switching unit having vertical terminals for engaging vertical plugging isolator contacts wherein the said terminals are interconnected within the said unit by at least one vacuum switch, and the vacuum switch has at least one terminal which is aligned with one of the said terminals of the traversible unit.

The envelope of the vacuum switch and the bushing of a retractable isolator contact form advantageously an integral insulating body. An external terminal of the vacuum switch can then also constitute a retractable The other external terminal of the vacuum switch may be connected by a conductor to an isolator contact which is retractable with the switching unit, and is spaced from the first isolator contact by a distance corresponding to the spacing between two stationary isolator contacts, connected, for instance, one to a busbar, and the other to a circuit conductor.

The main axis of the vacuum switch, parallel to its switching movement, is usually vertical. However it may be horizontal or inclined. Then external terminals at both ends of the vacuum switch can form retractable isolator contacts and can be spaced from each other corresponding to the horizontal distance of two stationary plugging isolator contacts.

For three-phase duty the vacuum switches can be contained in separate envelopes or a three-phase switching contact set can be contained in a common envelope. Three single phase vacuum switches or switching contacts can have their axes arranged in a vertical common plane to form a three-phase unit. Alternatively single phase vacuum switches or three-phase switching contacts in a common envelope can be located with their vertical axes parallel to each other at the corners of a triangle.

Walls or plates of insulating material can be provided between isolators to form phase barriers between them. The traversing can provide for earthing separately a busbar circuit and a consuming circuit through the unit.

For very high voltage duty two or more series connected vacuum switch contact pairs can be employed in the switching unit.

More details will become apparent and the invention will be better understood from the following description referring to the accompanying drawing, in which:

FIG. 1 shows partly in section, and by way of example, one phase of a three-phase circuit breaker embodying the invention,

FIG. 2 shows in a diagrammatic cross-section three vacuum switches of a three-phase circuit breaker according to the invention with their longitudinal axes in a common plane,

FIG. 3 shows an alternative arrangement wherein the longitudinal axes of three phase switches are located at the corners of a triangle,

FIG. 4 shows an alternative arrangement in which the longitudinal axis of the vacuum switch is inclined to the vertical, and

FIGS. 5 and 6 show details.

In all the figures similar reference characters indicate similar parts.

Referring to FIG. 1 a vertical plugging isolator arrangement comprises stationary isolator contacts 1, 1a connected respectively to a consuming feeder circuit, and a supplying busbar circuit. The two isolator contacts or terminals are located in separate chambers with a partition wall PW between them. An earthing terminal 2 is provided in a recess of the circuit chamber and an earthing terminal 3 projects downwards from the bottom wall of the busbar chamber. A truck 4 mounted on wheels or rollers for the traversing movement supports a unit 20 holding a vacuum switch 7 (three vacuum switches for three phase arrangements) enclosed in an outer casing or tank which holds the unit together. A lifting screw 5 enables raising and lowering the switching unit as known per se. Two or more vacuum switches can be connected in series or parallel and a common envelope may enclose two or more series or parallel connected contact pairs of the vacuum switch kind. In this example the switch is coaxial with the isolator, and both form an integral body, so that the upper switch terminal represents the retractable isolator contact. The switchgear is shown in a position in which it interconnects the busbar and feeder circuits. The circuit breaker isolator bushing 9 (three being provided for three-phase arrangement) is supported by the top wall of tank 20 and is horizontally spaced from the bushing 8 in accordance with the spacing between the isolator contacts 1 and 1a. A downward extension 11 of a movable contact of the vacuum switch 7 projects from the enclosure and is slidably connected through finger contacts 13 to a stationary conducting ring 12, situated at the lower end of the vacuum switch envelope and forming an external terminal of the vacuum switch. A conductor 10, which may be insulated, is provided to interconnect this ring terminal 12 with the conductor of the retractable plugging terminal which as shown engages the busbar isolator contact In.

The vacuum switch 7 is actuated by a pull rod 15 of insulating material and a bell-crank 14 from an operating shaft 19. The shaft 19 serves for simultaneous operation of three vacuum switches in three-phase arrangement.

Normally the vacuum switch contacts are closed by a spring 17 which brings the one end of a longitudinal slot 18, in a clevis or similar member, to bear against a stud at the left-hand end of crank 14. Switch 7 is rapidly opened when shaft 19 is clockwise rotated, for instance by a throw-off compression spring l6 whose release is controlled by a conventional switch latching and tripping means accommodated in a container 6.

FIG. 1 also shows a cable CA, a cable box CB, current transformer CT, high voltage transformer VT, an other current transformer CTa on the feeder side, also a relay panel RP and instrument panel IP on the busbar side. The circuit and busbar chambers and supporting panels may be of ordinary sheet steel construction.

According to FIG. 2 a three-phase arrangement may comprise a common insulating envelope CE made of ceramic material, or cast synthetic material, or of moulded pieces which are cemented together, and containing three single phase vacuum switches SW1, SW2, SW3 with their longitudinal axes positioned in a common plane. Isolator plugging bushings 9, 9", 9', corresponding to bushing 9 of FIG. 1, are then arranged in another vertical plane, and are mutually separated by insulating barriers PB1, PB2.

3 According to FIG. 3 three single phase vacuum switches SW1, SW2, SW3 of a three-phase arrangement have their vertical axes located at the three corners of a triangle, the plugging isolators 9, 9", 9 being here located at the corners of another triangle, with insulating barriers PB1, PBZ between the phases.

According to FIG. 4 the axis of a vacuum switch 7 is inclined in order to bridge the horizontal spacing between the vertical parallel axes of the isolator contacts 1, 1a. The external terminals of the switch 7 are vertical, and are aligned'with the bushings 8, 9 of the isolator contacts when the switchgear is in position for plugging. The vacuum switch 7 has now at the back end a ring which corresponds to the ring 12 of FIG. 1, and an external terminal for connection to the isolator contact is joined to this ring as shown in FIG. 4. Alternatively a pair of axially aligned external vacuum switch terminals can be used, if connectors are provided between them and the bushed plugging terminals. The operating mechanism and other details of the switchgear correspond to what has been described with respect to FIG. 1.

According to FIGS. 50 and b a joint between two electric conductors, positioned at a right-angle, such as required in conjunction with the present invention, for.

instance between hoirzontal and vertical sections of a busbar which forms the primary of a current transformer, can be insulated by embedding the joint in a synthetic resin casting SR.

Alternatively as FIGS. 60-611 show, an insulating tubular enclosure 1E of a conductor C1 is formed with annular projections P1, P2 which may have similar or dissimilar diameter, at opposite sides thereof. The projection P1 provides an opening for a conductor C2, which is coated with an insulating material and is joined to the conductor C1, using, for instance, bolts for which holes H are provided. When a conducting joint has been completed, the opening formed by the projecting ring P2 is closed using a plug of insulating material or a cast resin body CB, the opening at P1 being closed by the insulated conductor C2.

While preferred embodiments have been shown, variations are possible without departing from the invention as defined by the appended claim.

What we claim is:

In an electric power switchgear for high power, high voltage networks including a plurality of stationary vertical terminals spaced from each other a predetermined amount and a traversible switching unit, the improvemerit comprising a sealed container supported for horizontal traverse movement and for vertical plugging movement, 3. pair of terminal bushings extending upwardly from said container, said terminal bushings being in the same spaced relation as said stationary terminals for selective engagement'with a pair of said stationary terminals when said sealed container is traversed to a predetermined engaging position and is lifted to plug said terminal bushings into a pair of said stationary terminals, a vacuum switch within said container supported solely on one of the terminal bushings and extending coaxially therewith, an electrical conductor extending from the free end of said vacuum switch to the other of said terminal bushings, finger contacts supported on said vacuum switch and electrically connected to said conductor, said finger contacts slidably engaging a contact exten sion of said vacuum switch, and operating means connected to said vacuum switch for selectively opening and closing said switch.

References Cited by the Examiner UNITED STATES PATENTS 2,445,588 7/1948 Skeats 200144 X 2,749,410 6/1956 Weston 200144 2,810,805 10/1957 Schwager 200144 X 2,889,424 6/1959 Glore et al. 200-144 X 2,897,322 7/1959 Reece 200144 X 3,025,375 3/1962 Frank 200-144 3,163,735 12/1964 Miller 200-144 FOREIGN PATENTS 769,406 3/ 1957 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner;

KATHLEEN H. CLAFFY, Examiner. P. E. CRAWFORD, R. S. MACON, Assistant xwminers. 

